Rock drill bit



Odi. 26, 1937. R J. KlLLGORE 2,097,030

RRRRRRRRRRR 1T Patented Oct. 26, 1937 jUNITED STATES PATENT OFFICE :,osmao noon nBTLLm'r norm VJ. more, Los mem, cam.

Application December 15, 1934, Serial No. 757,701

1o claims. (c1. g55-s4) My invention relates in general to percussion drilling tools, and relates in particular to percussion rock bits of the type ordinarily employed in quarrying and excavating.

5 The invention may be used with percussion bits in which the cutting edges' are formed on the lower end of a drill stem or bar or are formed on a removable head adapted to be secured to the lower end of the drill stem or shank. The rst rock bits were made by forming the forward end of a bar of metal to a desired chisel form or to vwhat is termed star form. The cutting edges of such bits, being subject to very severe conditions of operation, rapidly dulled so as to make frequent resharpening necessary. To effect a saving o ver the old practice of resharpening cutting edges which were forged on the end of a bar of bit steel, we now find it relatively common practice to employ a drill stem or shank having athreaded lower end to which the rock bit or cutter is screwed.

It is an object of my invention to provide a further advance. in the art of drilling by the use of percussion bits by the production of aV rock bit having cutting edges which will drill further and maintain the gauge of the hole longer than the standard types of rock bits now employed.

Where a deep hole is to be drilled, it is cusstomary to start the hole with a large bit and to decrease the size of the bit as the depth of the hole increases. In such drilling operations it is important that the diameter of hole drilled by each bit shall be maintained as long as possible so that the bit diameters will not have to be decreased too rapidly for the depth of hole desired.

It is an object of the invention to provide a bit capable of maintaining its gauge for a longer period of time than standard bits and capable of decreasing its gauge at a slower rate than standard bits.

I have found that my new bit drills a much greater depth of hole than standard bits before becoming completely worn out. This beneficial result is in part effected by the ability of the bit to hold its gauge for a long period of time. The drilling of the hole is accomplished by the action of the cutting edges on the bottom of the hole, and my bit, by maintaining the gauge of hole so `that the bit may move relatively freely, enables the striking of a harder and sharper blow on the bottom of the hole, with the result that the drilling operation is conducted with greater rapidity and at a material saving in time, power, and labor.

It is an object of the invention tol provide a percussion type drill bit having downwardly and outwardly disposed hard metal inserts which preserve the gauge of the hole drilled.

A further object of the invention is to provide a bit of the above character in which the hard metal inserts are tapered inwardly and are seated in tapered openings formed in the bottom of the bit. I find that best results are obtainable where these tapered inserts do not bottom in theA tapered openings and are accordingly held against being driven into engagement -withthe bottoms'of the openings by the tapered side walls of the openings. Hard metals are ordinarily relatively brittle and tend to crystallize when subject to severe pounding action to which they are subjected in drills of this character. I find that breakage of the inserts is nearly entirely avoided by holding such inserts under very heavy radial compression,- which is preferably u obtained by seating tapered inserts in tapered openings so that the walls of the openings press forcibly against the inserts and tend to. compress the inserts radially as well as prevent or resist inward movement of the inserts in their tapered openings. 'I'hese inserts are preferably placed in thev openings while the bit bodies are heated, but they may be pressed into theopenings under great force.'

Further objects and advantages of the invention will be made evident throughout the following part ofthe specification.

Referring to the drawing, which is for illustrative purposes only,`

Fig. 1 is a partly sectioned elevational view of a rock bit embodying my invention.

Fig. 2 is a bottom plan view corresponding to Fig. 1.

Fig. 3 is an enlarged fragmentary section showing an opening or recess prepared to receive a hard metal insert.

Fig. 4 is a fragmentary sectional view showing an insert in the `opening prior to the grinding of the insert to conform to the configuration of the bit. y y A In Fig. 1 I show my invention embodied in a conventional detachableV rock bit I 0. Such bits are made with forged extensions ll .which will be hereinafter referred to as wings. The lower Y edges of the wings i I, whetherthere `be two or more in number depending upon the size of the bit, are sharpened after the manner of chisels tok provide downwardly faced cutting edges I2 which are driven sharply against the is an especial feature of the invention that the' inserts I3' are disposed in downwardly andeutwardly sloping diagonal relation and are in such position that the lower ends Il thereof form the corners or outer extremities of the cutting edges I2. Accordingly, these hard metal inserts may be made from selected metals in .accordancewith the materials to be penetrated, such, for example, as high speed steels, tungsten carbide, etc. Y

The inserts I! may, as shownin Figs. 1 and 2, be formed or ground to conform to the faces I5 forming the cutting edgesrand the end faces Il of the wings II. Each insert, having its exceptional wear resisting qualities, resists reduction of the gauge of the bit, and in addition to this valuable effect enables the bit. to render a greater service in actual penetration of the material or formation in which the hole is being drilled. Y e

In the preferred practice of making a bit in accordance with the principles of my invention, vthe body III is first formed from a 'steel which is selected for its toughness. YDepending upon the diameter of the bit, two or more wings `Il may be formed on the bit body II. In the drawing I have shown a bit body Ii of medium size having four wings II. Extending inwardly from the outer corner of each wing I I, a diagonal opening I8 is formed, as shown in Fig. 3, such opening being tapered inwardly and having a rounded bottom I 9. As shown in Fig. 4, aninsert 'IIa is secured in eachopening Il.

The insert in its original form as shown at Ila in Fig. 4 is sufficiently larger in diameter than the opening IB that the insert I3a will be firmly gripped by the side walls 2l of the opening I8 and will resist inward movement of the insert under the ordinary conditions vof operation encountered in the use of the bit. A preferred method of installing the inserts Ila. in the openings 58 is to heat the bit body I0 so as to expand the same.v The inserts are then forced into the openings to their desired positions,k and thebit .body is allowed to coolso that the walls 21| of the openings will shrink around or upon the inserts and placethe inserts under a very heavy radial compression. If the inserts I3a are initially made with the ends thereof blunt as shown at 22 in Fig. 4, the inserts after installation in the openings I8 may be ground oil' to provide relatively sharp corners 23,. as shown in Figs..1 and 2. I am cognizant of the fact, however, that where exceptionally hard` metal or alloy is employed in the inserts, it may be advisable Yto originally form the insertswith the ends thereof sharp.

I have found4 that where the inserts I3 are held in the openings 'I8 `by the gripping action of the tapered side walls 2| ofthe openings I8, and without the inner ends of the inserts bottoming ir. the openings I8, shatteringl of the inserts rarely occurs.v I do not intend to present the idea that the inserts must be at all times prevented from resting on the bottoms of the openings, as'I am aware that vin certain uses of my `invention the inserts may be made oi a material of such character that the inserts will not readily shatter in the normal use thereof. I believe, however, that it is at all times advisable to have the side walls 2| of the openings in constricting or compressing relation to the inserts which are held in the openings.

Although I have herein shown my invention in simple and practical form, it is recognized that certain parts or elements thereof are representative `of other parts, elements, or mechanisms which lmay be used in substantially the same manner to accomplish substantially the same results; therefore, it is to be understood that the invention is not to be limited lto the details disclosed herein but is to be accorded the full scope lof `the following claims.

I claiml as my invention: 1. A percussion 'rock bit of the character described, for use with means adapted to impart impact to the bit so as to drive the same against thev material t0 be drilled. comprising: a body -having means for. connecting it to said means for opening by the side walls of said opening.

2. A percussion rock bit of the character described, for use with means adapted to impart impact to the bit so as to drive the same against the material to be drilled, comprising: abody having means for connecting it to said means for imparting impact and having downwardly extending wings in opposed relation, said wings having downwardly faced cutting edges with diagonally inwardly and upwardly sloped openings leading from the outer endsA of said cutting edges;

-tending wings in opposed relation, said -wings having downwardly faced cutting edges with diagonally inwardly and upwardly sloped openings leading from-the outer ends of said cutting edges;

and an insert of hard metal secured in each of said openings in downwardly and outwardly sloping. relationv so that the lower end thereof-forms a corner of the wing in which it is secured.

4. A percussion rock blt of the character described, for use with means adapted to impart impact to the bit so as to drive the same against the material to be drilled, comprising-z a body having means for connecting it to said means for imparting impact and having a` downwardly extending wing with adownwardly facedcutting edge with a diagonally inwardly and upwardly sloped opening leading from the outer end of said cuttingedge; and an insert of hard metal secured in said opening in downwardly and outwardly sloping relation so that thev lower end thereof forms the corner of said wing.'

5. A percussion rock bit ofthe character described, for use with means adapted v`to impart impact to the bit so as to drive the same against of the hole cut by the rock bit.

6. A. percussion rock bit of the character describedJor use with means adapted toA impart impact to the bit so as to drive the same against the material to be drilled, comprising: a body having means for connecting it to said means for imparting impact and having downwardly extending wings forming cutting edges the `outer ends of which dene a circle, there being a diagonal, inwardly tapered opening extending inwardly from the outer end of each cutting edge ;v and a tapered hard metal insert secured in each of said openings, the outer ends'of said inserts lying in said `circle and operating to maintain the gauge of the hole cut by the rock bit.

7. A percussion rock bit of the character de scribed, for use with means adapted to impart impact to the. bit so as to drive the same against the material to be drilled, comprising: a body having means for connecting it to said means for imparting impact and having downwardly extending wings forming cutting edges the outer ends of which deiine a circle, there being a diag- 'l onal opening extending inwardly from the outer end of each cutting edge,v said openings being characterized by being open only attheir ends;

` and a hard metal insert secured `in each of said openings, the outer ends of said inserts lying in said circle and operating to maintain the gauge of the hole cut by the rock bit, said inserts being placed under radial compression and being held against inward movement in said openings by the side walls of said openings.

8. A percussion rock bit of the character descnbea, for use'witn means Yadapted to impart impact to the bit so' as to drive the same against the material to be drilled, comprising: a body having means for connecting it to said means for s imparting impact andghaving downwardly extending wings iormingcutting edges the outer ends of which denne a circle, there being a diagonal, inwardly tapered opening'extending inwardly fromthe outer end of each cutting edge; and a' tapered hard metal insert secured in each of said openings, the outer'ends of said inserts lying in said circle and operating to maintain the gauge of the hole cut-by the rock bit, said inserts being placed under radial compression and being held against inward movement in said openings by the side walls of said openings.

9.v A percussion rock bit :of the character described, comprising: a body having downwardly" extending wings forming cutting edges the outer ends of which dene a circle, there being a' diagonal opening extending inwardly `from the outer end of each cutting edge; anda hard metal insert secured in each of said openings, the outer ends of saidinserts lying in said circle and operating to maintain thegauge of the 4hole cut by the rock bit, said inserts being of vsuchv length that the inner endsthereoi' do not bottom in said openings, and said inserts-being held against inward movement in said openings by the side walls of said openings.

scribed, comprising: a body having downwardly extending wings forming cutting edges the outer ends of which deilne a circle, there being a diagonal, inwardly tapered opening extending inwardlyfrom the outer end of each cuttingedge; and a tapered hard metal insert secured in each of said openings,`the outer ends of said insertsV lying in said circle and operating to maintain the gauge of the hole cut by the rock bit, said inserts being 0:! such length thatv the inner ends thereofl do not bottom in said openings, and said inserts being held against inward 'movement inv said openings by the side walls of said openings. l

`ROBERT J.

, 30 i 10; A percussionrockbit ofV the character de- 

